Myelinated Nerve Fiber (mNFL)

File number: 58117

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Appears in: Imaging marvels
Condition/keywords: myelinated nerve fibers
Photographer: Ms Srishti Sharma
Imaging device: Fundus camera
Choithram Netralaya
Description: Myelinated nerve fiber layer (mNFL) is a benign clinical entity that results from an embryologic developmental anomaly. Myelination along the visual pathway is noted around the eighth month of gestation, and typically reaches the posterior globe around the time of birth with virtually all fibers reaching complete myelination by age 7 months till the lamina cribrosa. Sometimes, due to altered neuro hormonal signals, this process of myelination extends past the lamina cribrosa and is visible on fundus examination as distinct white patches on the inner retinal surface. On infrared and red-free imaging, mNFL appears white, which is likely due to the high lipid content of myelin. Myelin blocks detection of underlying fluorescent material, thus appearing dark on fundus autofluorescence. On optical coherence tomography , it appears as a thickened and hyperreflective retinal nerve fiber layer. mNFL is typically benign but can be mistaken for other potentially serious conditions like neoplastic infiltration or infection. Hence, it is crucial to recognize the benign nature of mNFL to avoid superfluous medical testing.